Aileen, it is October, anything bothering the leaves is not going to last long. When leaves senesce (get ready to drop), lots of things show up that might have been there. Also, new fungus move in, getting the almost dead leaves ready to decompose.

Best thing is to plant those 2 and wait for the spring. A few black spots are nothing. Even if the whole leaf looks weird in October, I wouldn't worry. Winter is coming and the old leaves are done for. If you do find you have blights, the best remedy is to clean up the area under the trees of the foliage and fruit.

Agreed, and dark spots on quince leaves are very common, sometimes occurring on the fruit also. Has not harmed my tree or fruit harvest in many years, although my spotting only occurs on fewer than a quarter of the leaves. Spotting tends to cluster on certain areas of the tree.